A Patch-Based Model For Urban Water, Carbon And Nitrogen Cycling (presentation)

BAND, L.E., C. Tague, D. Tenenbaum, N. Law, and S. Brun.

We present the conceptual framework and implementation of a watershed model of water, carbon and nitrogen (WCN) cycling within urban and urbanizing catchments. The model is based on a hierarchical model of the landscape with surface patches comprising the elemental response units. Soil-canopy-atmosphere cycling is treated at the patch level, taking into account net additions or abstractions due to horizontal flux. A patch network is defined for routing lateral flux of water, carbon and nutrients between patches, and includes the facility to incorporate storm and sanitary sewer systems as alternative and interacting flowpaths. The effects of constructed drainage systems can be seen in differences of surface soil water and saturation levels within the watersheds, with feedbacks to carbon and nitrogen cycling. Imports of WCN across watershed boundaries from water supply, and household consumption patterns are incorporated by estimating consumption patterns based on demographic information. The model provides the ability to investigate sensitivity of ecosystems along the urban to rural gradient to changes in the patch level cycling by direct human input or extraction, vegetation management, and other activities, as well as changes in the routing of WCN due to alteration of surface characteristics or drainage infrastructure.